Process of treating furs



Patented Oct. 17, 1933 Q ,355 PROCESS OF TREATING FURS Alexander Nathansohn, Beriin-Wilmendorf, Germany at Drawing. Application Mas-c118, 1932, Serial No. 597,845, and in Germany March 17, 1931 The invention relates to a process of improving furs by extending or straightening the hair by treating the skin with formic acid, acetic acid. etc. 7 v

I It is true that it has previously been proposed in improving furs to use acetic acid or formic acid for enhancing the lustre, and acetic ether,

ie which it has been customary to add other substances, has also been employed for the 10 same purpose. This treatment, which was intended to impart to the pelt the so-called lustre had to be carried out, however, with dilute aqueous acids in order to attain the desired object. 7

In contradistinction thereto, in the process according to the invention; for the purpose of attaining a fundamentally diflerent object, namelythe straightening of the hair and more particularly the under-hair, the formic acid or acetic acid (i. e. lower saturated aliphatic acid) employed in the process should be usedin the technically water-free or anhydrous condition, and a dilute solution of the acid in acetic ether should not be used. On the contrary. formic, as acid is used for example in the form of a saturated solution of the acid, containing not more than about 5% of water, in benzin'e containing about 1.4 per cent of formic acid; or aceticacid in the form of a20 per-cent solution in thesame solvent. The pure, water-free acids may also 'be used, but this, however easily leads to injury to the hide. The .process should be carried out either by immersing, the skins in question in-the solution, or the vapour of the 5 38 solution may be allowedto act upon the skins,

if desired,- with slight heating. In the latter case, it is preferable, to heat the room, in which is situated the material to be treated, to a temperature of about C.

40 The *eiiect of the process diflers according to room temperature in a formic acid bath of the above-mentioned composition, and the desired eifectis-observable generally after only a quarter of an hour. A longer time, for example eight hours-or more, is required in-the acetic,

acid bath. 1: the vapour of the said liquids is used, the eflect, if it is to be durable; requires veral hours "at 40 C. as a rule. The length of time required for the effect is-not quite the. same, depending upon the type of pelt and its previous treatment, and must'be found by trial in each particular case. I

skins with curly hair, more particularly sheep skins, react to the process, irrespective of the f form in which it is employed, in the case of considerable intensity, by complete straightening of the hair, such that, for example, it ispossible to impart the character of a mufllon to a slink. Whether this last process is economical will depend upon' the fashion, that is to say,

has suflered by the dressing operation and above all by bleaching, the hair recovers its former Persian lamb character when the new process. is carried out in a correctly controlled manner. Inaddition, the hairofskins which have a dead appearancedue particularly to bleaching regains its ori in l character. The hair is lustrous as itis calledin the art, and the opaque appearance of many over-bleached skins isagain replaced by the original optical character. The

most important phenomenon of the new process,

however, is at all events the straightening of the hairin contradistinction to the mere production of lustre which was attained bythe processes known heretofore. I

ascomparedwiththeoldprocesshcwever g' there is a fundamental difference not only in ume of ethyl acetate (acetic ether) is added.'

the straightening within the stated time is much less-pronounced, and if 10 per cent. is added instead, there is no straightening at all. .If ethyl 119 acetate (acetic ether) is employed as solvent for formic acid, there is not evena trace of the characteristic eflect to be seen. Exactly the same inhibiting eflect as that exerted by ethyl acetate (acetic'ether) is'observed on using diethyl ether, ethyl alcohol andacetone. Here again, an addition of per cent. is tolerable,

but agreater addition is not. Acetaldehyde is I still permissible in a concentration of per cent. but it also inhibits the efiect when the concentration is greater.

As principal diluents for the acids, it is possible to employ hydrocarbons other than henzine, such as benzene or the like. Completely.

or partly chlorine-substituted hydrocarbons,

such as chloroform or carbon tetrachloride may also be used.

Water should not be used for dilution. but

I according to, what has been stated hereinbetore,

treating skins with substantially anhydrous lower aliphatic acid.

2. Process as in claim 1, in which the treating occurs with substantially anhydrous formic acid.

3. Process as in claim 1, in which the treating occurs with substantially anhydrous acetic acid.

the acid is in'solution in a hydrocarbon.

5. Process as in claim 1, characterized in that the acid is in solution in a chlorine-substituted hydrocarbon.

6. Process as in claim 1, in which the treating occurs in the presence of an oxygen-containing organic substance, in a concentration of up to 15 percent, for retarding the process.

7. The process for treating furs for extending or straightening the hair, which includes treating the skins by immersion in a substantially anhydrous solution containing lower aliphatic acid.

8. The process for treating furs Ior extending or straightening the hair, which includes treating the skins by exposure to the vapors of sub stantially anhydrous lower aliphatic acid.

ALEXANDER N ATHAVSOHN 4. Process as in claim 1, characterized in that 

